A known vehicle roof device disclosed in such as JP2000-185554 A is illustrated in FIG. 4. A basic configuration of the known vehicle roof device will be explained in accordance with FIG. 4. The known vehicle roof device includes guide rails 2, brackets 3, bolts 4, a frame 5 and caulking portions 6. Each of the guide rails 2 is provided at a vehicle roof 1 along a side of the opening portion and fixed to the bracket 3, which is provided at the side of the vehicle, by means of the bolt 4. The frame 5 made of a steel plate and extending in a vehicle width direction is provide at the rear portion of the opening portion in a manner where each end portion of the frame 5 is fixed to each guide rail 2 by means of the caulking portion 6. The frame 5 may be fixed to the guide rail 2 by means of welding or screwing.
In this configuration, because the frame 5 connects two guide rails 2 provided at the opening portion, chances that the roof deforms when an excessive load is applied to the vehicle, especially near the pillar, upon, for example a vehicle collision, have been reduced. Thus, the frame 5 is made of a steel plate having an appropriate thickness in order to reduce the chances of a deformation. The guide rail 2 is made of aluminum base alloy and formed by way of extrusion molding so as to include a groove 7 and a side groove 8. A shoe connected to a sunroof rid is provided within a groove 7 so as to be slidable in a front-rear direction of the vehicle, and a side edge of a sunshade is housed within the side groove 8.
As described above, the frame made of the steel plate is joined to the guide rail made of aluminum basic alloy by means of caulking, welding or a bolt. However, because the thickness of the frame needs to be set at an appropriate value in order to avoid its deformation, it has been considered that caulking is not an appropriate method for joining the frame to the guide rail. A need thus exist to provided the vehicle roof device whose frame can join to the guide rail by caulking.